IC-MHL200 Datasheet, PDF (15/33 Pages) IC-Haus GmbH – 12-BIT LINEAR / ROTARY POSITION HALL ENCODER

iC-MHL200
12-BIT LINEAR / ROTARY POSITION HALL ENCODER
20
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Rev C1, Page 15/33
NCOS PSIN PCOS NSIN
SP_B
SP_C
SP_B
SP_C
SP_C
SP_B
SP_C
SP_B
SP_C
SP_B
SP_C
SP_B
NCOS PSIN PCOS NSIN
SP_B
SP_C
N
SP_B
SP_C
SP_C
SP_B
SP_C
SP_B
SP_C
SP_B
S
SP_C
SP_B
N
0°
1
Figure 7: Position of the Hall sensors
1
Figure 8: Zero angular position of the magnetic tar-
get. Center of south pole is aligned to the
PCOS sensor pair
The field distribution can be approximately described as
a sinusoidal variation of the magnetic field strength B
along the target. As mentioned before, the iC-MHL200
provides analog sensor signals V_SIN and V_COS which
represents the linear position of the tape with respect to
the chip. The signals are internal but can be made ex-
ternally available for test purposes (see the description
of calibration procedure).
The definition of a specific moving direction can be
made by comparing the mechanical position with the
corresponding electrical angular value. To obtain in-
creasing angular position values, the magnetic tape
has to be moved to the left (when looking on top of the
chip/package) as shown in Figure 9 where the tape has
been shifted 1 mm to the left, as compared to Figure 8.
These signals are derived from the output signal differ-
ence of the complementary sensor pairs (PSIN/NSIN
for the sine signal, PCOS/NCOS for the cosine signal)
resulting in
V_SIN = V_PSIN - V_NSIN
and
V_COS = V_PCOS - V_NCOS.
Since the field distribution repeats periodically every
4 mm, an absolute position value can be defined only
within a range of one magnetic period. Electrically, the
sensor signals are repeating every 360 ° for every target
movement of 4 mm.
20
NCOS PSIN PCOS NSIN
N
SP_B
SP_C
SP_B
SP_C
SP_C
SP_B
S
SP_C
SP_B
SP_C
SP_B
SP_C
SP_B
N
90° 0°
By definition, the electrical zero position (within one pe-
riod) is given by the corresponding angular zero value
ϕ = 0 where V_sin is zero and V_cos is at its maximum
value. The mechanical zero-position location of the
tape with respect to the iC-MHL200 is shown in Figure
8.
1
Figure 9: Position of the magnetic target at 90 ° elec-
trical position. Center of south pole is
aligned to the PSIN sensor pair